Holiday Shipping & Returns Policy

Holiday Returns Policy

Just in time for the holidays, we've extended our normal 30-day return policy. Any order placed between November 25, 2016 and December 25, 2016 will be accepted for return until February 5, 2017. RMA numbers will be given out until 7:30 PM EST on February 3, 2017. The remainder of our return policy remains in place and must be followed. Please review the rest of our return policy

Gift Certificates by Christmas

Physical Gift Certificates: order by 5 PM EST on 12/18

Electronic Gift Certificates: order by 5 PM EST on 12/23

Custom Bama Chip/Tuner and Mounted & Balanced wheel and tire orders must be placed no later than December 14th, 2015 to ship free for Christmas delivery.

*Free Christmas Shipping is free / guaranteed to arrive by Christmas for the lower 48 states only. APO / FPO and Canadian, Guam, Puerto Rico, US Virgin Islands Customers: Unfortunately we are unable to guarantee shipping times to your addresses, so the above deadlines do not apply. Items being shipped via freight also cannot be guaranteed in time for delivery.

Product Resources

High Flow. Are you looking to free up your restrictive exhaust, but are required to use Catalytic Converters? AmericanMuscle has the answer in the form of SLP's High Flow Ceramic Catalytic Converter Kit.

Durable Construction. These SLP Catalytic Converters are made out of Stainless Steel and a durable Ceramic substrate material making them perfect for naturally aspirated applications.

Will pass most emission tests. SLP's High Flow Ceramic Catalytic Converters will pass most states emissions testing procedures. However, check your local and state ordinances for installation and usage regulations.

Application. This SLP High Flow Catalytic Converter Kit is designed for use with Mustangs from 1996-2010 and is sold as a set of two.

Most Helpful Reviews

5/5

SLP Cats

I have a MAC Catted H-pipe. Found out 2 weeks ago that one of my cats went bad that came with the MAC H-pipe. ordered these SLP cats to Replace the old cats and I have no complaints! (yet i Guess...lol) ...
I had the old cats cut out and the new SLP Hi-Flow cats welded in. The sound is still agrressive and Im sure they perform just as well..if not better..
NOTE: SLP says that these cats are made ONLY for fitment with SLP X-pipes. This is not the case..you can pretty much have them welded in in any set up...

These will fit in fine. I believe they are the same length so you should be able to cut out the old and slip these right in. Not sure if you're aware but, your car has two resonators right off of the exhaust manifolds. These then dump into the converters and out from there. The resonators are offset a bit so these will not be a direct fit at that location.

Will it fit? Would my exhaust be louder? I have a 97' V6 which has a pre cat and then the cat. Is it possible If I could just take off the pre cat and replace my 2nd cat with this Slp high flow cat. And if possible then what kind of performance/ loudness gain am I looking at? (By the way, I have dual Slp Loudmouth mufflers installed)

Evans1997

I recommend leaving the pre-cats alone, chopping off the rear cats and straight-piping it. Have holes drilled in the pipes for the rear O2 sensors, get mil-eliminators to to attach to those, (takes care of CEL) -you will see a huge performance gain! If you still prefer your way, have the shop cut open the pre-cats and gut the ceramic mesh inside, then weld them shut again. This way you could lop off the rear cats and toss the high-flows on and it'll be quite cheaper. Yes car will be louder, but not anything that will get you pulled over. Hope this helps :)

Will this set fit onto my JBA off road pipes? And if they fit the JBA off road pipes will i still have my sound that i have or will it sound better??
thank you

Mikekaye1969

These will slide on to any 2.5" pipe between the header/manifold down pipes and the mid-pipe, and clamp or weld in. Catalytic converters have little effect on the exhaust note. Overall, your sound will not be affected.

The SLP High Flow Catalytic Converter Kit is a universal kit designed to work with all 1996 to 2010 Ford Mustangs with some modification. This kit should work fine with your off road x pipe but you will have to modify the X pipe and your exhaust to weld or clamp these Catalytic converters in.

Let me start by saying these things sound great! Definetly added a little roar to my 3.8. Not to mention, a little power boost is noticed. On the other hand, my engine light popped on and I definetly noticed a reduction in gas mileage. Be Cautious!

Delivered on time and neatly packaged... I was looking for something that wouldn't make my car sound so low and these definitely did the job.. if anything they make my car sound so much better.. definitely recommend if you're looking to keep your car sounding loud..

Bought these to accompany the gutted primaries on my '02 P71, eliminated overly loud exhaust and gave me my low end torque back. Roasted the tires for 5 seconds before the car even came off the line! I plan on throwing an X pipe and a pair of Pypes M80s mufflers on in a couple weeks. Thanks American Muscle!

This is a great product, no only will help you to get a little more HP, but it will as well help you with the sound. I already have SLP LM1 and they sound great with the stock CATs, But still not that off-road sound that I wanted. I bought this specially because of the SLP brand and the reviews. I cannot be more happy with them. The sound is the nearest you can get to an off-road sound (with the SLP LM1 combo) I will upload a Video latter so you can judge for yourself s. The installation requires a 5 inch pipe so it can fit your stock mufflers if you are removing your stock cats. Other than that it took my welder about 20 minutes to have both cats welded.

I got these to make my exhaust smell and sound better and to be legal. The bbk o/r x pipe sounded terrible with stock mufflers and smelled worse. It was an easy install with a saws all and clamps with good fitment. It toned down the rasp but is still louder and smells almost stock. I feel a little more power compared to stock exhaust. Recommended!

I have a MAC Catted H-pipe. Found out 2 weeks ago that one of my cats went bad that came with the MAC H-pipe. ordered these SLP cats to Replace the old cats and I have no complaints! (yet i Guess...lol) I had the old cats cut out and the new SLP Hi-Flow cats welded in. The sound is still agrressive and Im sure they perform just as well..if not better..
NOTE: SLP says that these cats are made ONLY for fitment with SLP X-pipes. This is not the case..you can pretty much have them welded in in any set up...

Overall great product with great customer support. AM price matched it for me and everything. I ended up writing an install guide for the cats in hopes to make the installation for others a bit easier. Only reason why I gave it 4 stars is because no installation hardware came with the kit. You either need to have them welded in or you need to purchase 4 exhaust clamps. (I bought 4 for $8)

I had these cats welded on to my bbk o/r x pipe and no complaints at all. Top notch SLP quality, makes a non-catted x pipe sound so much better throughout the rpm band, no more rasp with my exhaust and sounds much cleaner

I am extremely happy with these high flow cats. I was concerned will losing clearance under my 2008 Mustang, but the size of these cats matched the stock cats. This allowed them to be installed right where they are from the factory. Even though they are not large enough to place the O2 sensors, they can still be mounted just behind them on the pipe. Now I have that high performance, that great sound, and maintain my states requirements, exactly what I was looking for.

This things are everything you would expect from SLP. I have them custom welded into a bbk x-pipe with loudmouths and I couldnt be happier with it. they give me the sound and the quality i was looking for

I added them into my bbk o/r x pipe (long tube headers, Flowmaster 40s) They sound great.
Here is the problem My stang has the lowering springs. The drivers side cat has to sit about a inch and a half lower for the tranny linkage than the passenger side This puts them less than 1 1/2 inches off the road. and have scraped them on the road a couple times now. I don't even dare go over a speed bump. I really wish i could keep them they do sound great and I'm not setting off car alarms in the parking lots anymore
I am going with the MagnaFlow HiFlow Cats they are a lot smaller in diameter

Easy to install. I had the X-pipe off the car, but then completed the install laying on the ground with the car on jack stands. Still pretty easy considering. Came with detailed instructions. About a 1/2" better clearance than the ones I had on previously (don't know the manufacturer) because these have a flat spot on the bottom. I still took a hit on a speed bump causing a dent, and it held up. No funny sounds indicating it cracked inside. My old one cracked and sounded horrible.

These converters fit perfectly right out of the box and improved the performance. I had the exhaust system completely realigned while I was having the converters installed. Sounds unbelievable and my performance it off the charts. This was a 5 Star purchase. Love them.

Meet Our Team

I have always been a motor head. My parents told me my first word was “car”, and growing up I always had a toy with 4 wheels on it! My grandfather was also a big motor head and me being the first grandchild (and the only other person who had the car gene in the family) I was soon the companion for...